I have done that on 6 or 8 loads I worked up for my 7X57 Mauser, and I'm wondering if that's why ALL of my primers look flattened, even when shooting starter loads.

I had no other signs of excess pressure, even with my max loads.

Could it be that the (still) lubricated brass releases from the chamber walls when fired, allowing it to slam backwards into the bolt face?

And if that is the likely cause of the flattened primers, would I need to work up to max loads cautiously if I clean the lube off the brass? I'm thinking the pressures generated would be higher if the cases expanded and remained in the forward position rather sliding rearward to the bolt face. Or not?

In other words, is it necessary to remove case lube before firing reloaded ammo?

Why, or why not?

__________________
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Lubricated cartridges have two adverse effects that will show up as higher chamber pressure:
The lube allows the case to set back against the bolt face with full force, nothing taken up by friction of the brass case against the steel chamber.
The lube fills the space between brass and chamber with incompressible material, reducing the effective chamber volume.
These appear to be small effects but they do add up.

Bear in mind that British proof law calls for firing with oiled cartridges to maximize the load on the gun. Also their axial pressure test rigs depend on oiled cases to deliver all the chamber pressure as bolt head thrust so as to get a good reading.

Put your cases back in the tumbler for 10 mins after sizing to remove lube and dont forget to push out all the bits of media that are blocking your flash holes after! (some people tumble loaded rounds to avoid cleaning flash holes, but even mentioning this will probably bring on the flames )

Good morning
Then there is the dirt factor. Microscopic dust particles will redily adhere to the case. Maybe where you are at that is a no problem. Here there is volcanis dust... nasty gritty abrasive that takes the paint off a car hood curve in just a few years. You do not want that stuff grinding away in your chamber.
Mike in Peru

I'm not sure how much of the lubed case = dangerous bolt thrust concept is real, and how much is tradition. But this analysis (and the tests that are hyperlinked) would say it is relatively small (~4-6%). Countering that thrust increase is the reduced stress on the brass/case stretch

Anyone else have more data/other tests (maybe even a strain gauge on the bolt/lugs somehow)?

Firearms are not designed taking into account case friction. Lets say you are to design a firearm, what % case friction do you use to weaken your mechanism? Pick a number. What ever number greater than zero that you pick will be wrong because you cannot control the shooting environment. It might be raining when the weapon is fired, the shooter may sneeze on the ammo.

Col Townsend Whelen and General Hatcher are the reason Americans are worried about greasing bullets and oil on cases. In 1921 the Army experienced blowups with national match ammunition the bullets of which were coated in tin. These were called the Tin Can ammo. Instead of focusing on the cold welding between the bullet and the case, which caused a bore obstruction, the Army decided on a cover up. They blame shifted the problem to competitive shooters who were applying grease to their bullets in an attempt to reduce bore fouling.

The Army ran bogus pressure tests, “proved” the only problem was the civilians and greased bullets, banned greased bullets from competition, and created a bogus legacy that has lasted for decades. Col Townsend Whelen was in charge of the development and manufacturing of the Tin Can ammunition. As would be expected from a man who made a very visible mistake but absolutely denied any responsibility for his actions, for the rest of his gunwriting life he constantly warned that greased bullets and oiled cases “dangerously” raised pressures. If you have ever read Hatcher’s Notebook you will also notice how cleverly Hatcher misdirects, obfuscates, and blame shifts the problems to the shooters, not the Army Ordnance Department.

Gunwriters have parroted Hatcher and Whelen for decades. Gunwriters are at best Journalist majors, they don’t have the technical background to understand gun design. They never consider the early mechanisms that used oilers, modern mechanisms that use chamber flutes, externally lubricated bullets (such as .22LR which the entire case is waxed), moly lube bullets, paper hull shotgun shells which are heavily waxed, and in fact they have created derivative myths, such as case friction is necessary not to overload mechanisms. That is where the rough chamber myth came about, which is a bogus as you can get.

I think that came about from P. O. Ackley’s promotions of his Ackley Improved Cartridges by shooting a case in a rifle without a locking lug.

Ackley was taking heat because he was getting high velocities from his improved cartridges, cartridges which were being used in actions not designed for the things. P.O. wanted to show that his speedy cartridges did not increase bolt thrust, and infact as a result of his experiments, claimed they actually reduced bolt thrust. Which was bogus as heck as these improved cartridges actually ran at higher pressures. Higher pressures increases bolt thrust, it does not lessen it.

Read carefully “Yielding of Brass Case Walls in the Chamber A Technical Note”, 30 June 2009 James A. Boatright http://www.thewellguidedbullet.com/m...al_studies.htm .Mr Boatright shows how a 308 case, in a clean chamber, can lock in and hold pressures by itself up to 25K psia.

However once pressures go above 25K psia, the brass case stretches and if not supported, the case head will blow off.

If you notice, P.O. Ackley never conducted his test with a 30-06 or a similar high pressure cartridge which would have blown right out his lug less rifle. Instead ole P.O. was interested in promoting his cartridges and left a very misleading legacy in terms of case friction, load, and chamber roughness.

There are a number of fielded weapon systems that used lubricated cases.

Gentleman, that is a Japanese Nambu Machine gun. And on the top is an oiler. This fielded weapon killed lots of Americans and performed satisfactorily throughout the China/Burma/India theater and the South Pacific.

I have shot lubricated cases for several decades in my M1a’s and Garands. I do this because these mechanisms are hard on cases, stretching them so badly that five reloads is a good rule thumb for cases in this mechanism.

I took one set 22 reloads and never had an indication of case head separations.

What I found in developing loads was that the primers in lubricated cases were rounded, whereas in a dry case, the primers were flattened. Obviously the pressures were the same. I am of the opinion that with dry cases the primer backs out, the case stretches and stuffs the primer back in the pocket. With a lubricated case I think the case and primer both move to the bolt face at the same time. But this is based on a cartridges where I set the shoulder back .003". If your primers are flattened I would suspect high pressure. Or maybe you have created huge headspace in your cartridges. I develop my loads with lubricated cases. When the primers flatten, I know I am near a max load.

Excessive headspace will result in peening. Lubricated cases or dry cases. The dry cases will simply be stretched to the bolt face, lubricated cases will slide. If the headspace is excessive you can expect action peening. That is why it is important to control the headspace of your cartridges and rifles.

I highly recommend you buy a cartridge headspace gage and set up your sizing dies using the thing.

Some of your arguments are somewhat reasonable but some of your examples are realitively low pressure(compared to about any modern rifle cartridge) and the presence or lack of lube on the case would not make much difference. I believe it has been proven that a straight bodied case will produce less bolt thrust than a tapered body case. Many full automatic firearms from the early 20th century required lubed cases for proper function and these specific design features do not prove your point. These systems were integrated into the design or added to remedy some malfunction in extraction, neither of which is a factor in a modern hunting rifle.

Now size a case and adjust the die until you are setting the shoulder back 2 or 3 thousandths.

You will also want to polish the expander ball so it reduces friction so that when you pull the case out, the expander ball doesn't pull the shoulder forward.

Or you could completely remove the expander ball and turn the necks which removes material from the outside of the neck. This reduced diameter means that the neck doesn't get sized down as much, which negates the need to expand it back out.

Or you could buy dies that use bushings to accomplish this.

Anyway, if headspace is set correctly, flat primers become a thing of the past. Even with loads that are too hot and start giving hard bolt lift.

And do yourself a favor and get a chronograph. Without a chronograph and a way to measure headspace, you are basically flying blind.

I love it when reloaders declare an exemption to a rule, about 10 years the slide and glide shooters became the rage, they declared greasing your bullets eliminated case head separation or stretch between the head of the case and case body, reloaders got giggly over the thought and some got so excited they quoted Hatcher, none of them had a clue as to what happened to hatcher and his experiment, I claimed I have never read Hatcher, to do so would provoke those that think they understand to accuse me of not being able to read.

Anyhow, it is a .7854 thing, eliminating head space does not eliminate signs of pressure when reading the primer, it is a matter of keeping up with more than one thought at a time. I am the fan of cutting down on all that case head travel, after eliminating case head travel I still have case head travel.

If the brass was washed with soap, I would think the lube would be cleaned off, but not in a tumbler full of corn cob.

Try it.

Reloading is a game of science. Resorting to "I think", "I guess", and other uncertainties won't result in any real data being submitted for discussion.

I use Imperial Sizing Wax. If I leave the lube on rifle cartridges, I get signs of over-pressure with low charge weights. If I run the cartridges (or brass) in my walnut media for 10 minutes, I can run that same load all the way up to max (or higher).

I tried it, and formed an opinion based on data. Reloading is all about the data. If you don't have data, you don't have anything.

__________________"Such is the strange way that man works -- first he virtually destroys a species and then does everything in his power to restore it."

Looks like you knew what you were doing wrong from the get go . Wipe them down with mineral spirits or plain old Ronsonol lighter fluid as soon as you resize . Then you don't have to trim and load greasy cases ( this is how primers get fouled ) . Some guys tumble to remove case lube ( shortens life of media ) . If the case can't get a grip on the chamber it's going to tell you all kinds of lies

Some of your arguments are somewhat reasonable but some of your examples are realitively low pressure(compared to about any modern rifle cartridge) and the presence or lack of lube on the case would not make much difference.

If their claims were true then it would be true regardless of cartridge and mechanism. Yes a .22LR is low pressure, but that is only relative to something like a service round. The case is the weakest link, raising pressures on a rim fire will result in blown case heads and sidewalls just as would happen to a thicker skinned cartridge.

If a Nambu is not considered high pressure, what about a machine gun that was chambered in 8 X 56 R, 8X57 mm and 6.5 X 55 mm? The Schwarzlose used an oil pump mechanism. Some pretty good pictures of a Schwarzlose is at this URL. The oiler is on the top cover, with the top cover removed you can see wonderfully machined parts.

The Schwarzlose machine gun has a device for oiling each cartridge to ease the reloading cycle. On each stroke oil was squirted into the firing chamber to lubricate the incoming cartridge case.

1912 some changes were made to the feed system and this change was called M1907/12. It had a straight top receiver and a simplified oil pad system instead of the pump mechanism.

DoD experimented with lubricated cases, this section is from AMCP 706-260, Automatic Weapon Design.
There is an excellent section on lubricated cases in section 6.0 Blowback in “Brassey’s Small Arms” by Allsop and Toomey. http://www.amazon.com/Small-Arms-Mac...9809941&sr=1-1 Or if you want to design a firearm, start with this book by Brassey’s “ Brassey's Essential Guide to Military Small Arms: Design Principles and Operating Methods”http://www.amazon.com/Brasseys-Essen...9809941&sr=1-2 It is only $500.00 but the information on bolt lug design is priceless.

As for high power, is a 20mm cannon big enough? Brassey’s Small Arms references two automatic cannon that used lubricated cases. These cannons used cases that were greased. No oilers, greased ammunition.

How could that be if Hatcher and Whelen were telling the truth?

We don’t see oilers and greased cases anymore because they were designed out. During WWII the Germans used fluted chambers which use gas lubrication to break the friction between the case and the chamber. (You want to gum up a G3 just let those flutes get dirty) Instantly oilers and lubed cases were obsolete. This has been so long that oilers and greased cases are beyond living memory, which allows ignorant XXXX’s like Dick Culver to write historical fiction stories, the plots of which are based on lies.

Fluted chamber used on the HK91

Also used for "low powered" applications.

Quote:

I believe it has been proven that a straight bodied case will produce less bolt thrust than a tapered body case.

Ah, no. Proved by whom?

I believe that many of the factory cartridges we use are coated with ceresin wax. The same case lubricant used on the Pederson rifle cases. I believe it is there to keep the cartridges shiny. No one wants to buy brand new ammunition that is tarnished, and based on spider webbed corrosion I have seen on some of my older factory ammunition, which only occurs under films, I believe those tricky dudes at the factory are spraying finished cartridges with a very thin wax coating.

I do not get giggly with all the glitter and bling, and for sure I do not get excited about the cartoon illustration demonstration, the trigger is pulled and then there is the sequence of events, my firing pin crushes the primer first before the bullet, case and powder know their little buddy, the primer, has been hit. The cartoon looks like a Batman and Robin cartoon with all the stars, flashes and jagged lines.

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